Recently, attention has been paid to sunlight energy with a view to saving energy or achieving clean energy, and active research and development have been undertaken for its effective utilization in various fields.
As an example, the present applicant has already come up with various techniques whereby sunlight energy is focused through a lens etc. into a photoconductor and transmit it therethrough to a desired place where it is used as light energy for the purpose of illumination or other purpose.
In the art, the technique has also been introduced, whereby the light is permitted to strike upon an induction substance to induce a photochemical reaction in that material and thereby accumulate the resulting light energy, and the thus accumulated energy is thereafter recovered as heat energy with the use of a catalyst (for instance, see Japanese Patent Publication No. 57-124657), and those skilled in the art have had increasing interest in that technique. It is thus feasible to use sunlight energy as heat energy, if the sunlight energy is accumulated in the induction substance
However, when it is desired to accumulate solar energy in the induction substance, there is a fear that the photochemical reaction may not take place over the induction substance since the intensity of the sunlight varies depending upon weather and time. This is particularly true of the case where the sunlight energy is feeble. As a result, the amount of energy to be accumulated in the induction material is so reduced that a uniform and efficient build-up of energy may be unfeasible.